02 liberty 3.7 dies intermittantly - HELP! I'm out of ideas...

[LibertyCentral]

I have an 02 liberty, with 3.7 and auto. I've rebuilt the motor, had the trans rebuilt and a lot of other replacements/repairs back in early 2018. It ran great for a year or so.

This winter, around the time of severe cold, I had to replace the battery. I also ended up putting it on a charger/booster unit to get it started. I only mention this due to the approximation of the time the issues started. I can't say for certainty the battery replacement was the exact time this issue started but its near.

What happens: I drive the jeep, no determined amount of time and suddenly it dies. Sometimes it starts right back up, other times it takes a few minutes of sitting before it starts up again. It will crank over fine just not fire.

Things I have tried for isolation:
-Fuel pressure - Good when it dies, stays consistent at about 50psi even when it has to sit.
-I have a viper remote start/alarm system. Pulled the fuses for this in case it was defective. No change
-replaced the PCM thinking maybe I fried it with the battery boost/replacement - no difference
-had to replace the TPS, had thrown a code but I think it was a victim of when it failed and I pumped the pedal trying to get it to respond. I broke the old one trying to remove it for inspection.
-wiggle test on various sensors/wires
-replace the oil pressure sender, due to leakage (oil light does not come on prior to fail)
-swapped the ASD relay - no change.
-No codes are set by this event. I have had some codes in the past but these have been present when it ran ok.
They are:
P0442 - evap small leak
P0445 - evap gross leak (hoses by tank need replaced)
P0734 - gear4 incorrect ratio. no idea why this pops up, it runs fine
I've had a code 18 and some other bus related error but that was a one off and not at the time of the issue.

When it dies, it can be sitting at a light, driving highway speed, driving city speeds, basically no pattern to it. In all cases the engine was warmed up so it should be in closed loop.

In desperation I took it to a shop for further diag and they put about 90 miles on it over 2 weeks. It ran perfect for them of course. I got it back, one trip to the store and it starts the dying issue again.

Other times I can drive for hours and it never happens.

I'm lost on this one, if anyone has ideas on what to try I'd love to hear them. I've debated replacing the cam and crank sensors but if they were faulty I'd expect a code logged to them as well. The other thought I had was to jumper the ASD relay to see if it will run through whatever issue it has and throw up a code.

 

[HoosierJeeper]

Does it sputter out and die? Or just flat out abrupt die? I'm wondering if you have a bad ground that's just killing it.

 

[dillon]

i have a hunch it's crank sensor but no codes doesn't back up my hunch unfortunately...

 

[LibertyCentral]

Thanks for the feedback so far!

It does not sputter, it flat out shuts off. Like a key off. One second running fine, the next nothing.

I also considered the grounds, they look ok, and the shop also verified they were ok. But, its a good thought, I'll double check them again.

Crank sensor came to mind for me as well, but due to lack of codes I'm not convinced thats it either. It may be worth just replacing it anyway to remove doubt but I hate to get into "throw parts at it" mode.

 

[Billwill]

Could be the Cam or crank sensor or a wire shorting to chassis sometimes or a bad pin in a connector.

It could be voltage related. Plug your multimeter into the front cigar lighter/power output so you can monitor the battery voltage while driving. I had several wiring problems that would cause the voltage to rise up to 17 volts at which time the engine cut out...2002 Export CRD!

This was usually initiated by me doing something...switching on the front wipers would make the voltage slowly rise...switching on the aircon etc. By the time I ended a long trip on the open road my battery had boiled itself to destruction.

Difficult to find such a problem but worth checking the voltage while driving.

 

[dillon]

I had an old explorer that would cut out if i put brakes on going downhill. the wire to crank sensor would shift forward and short out on a pulley and the truck would shut down. no codes.

 

[LibertyCentral]

Ok, latest attempts to do SOMETHING with this Liberty...

Replaced cam AND crank sensors. No change.
Grounds verified again, all good, no resistance between engine and body.
Voltage was ok, no over volts, runs about 13.7 when running.

I did possibly capture a few frames of an event when it died but I'm not quite sure this tells me anything.

Frame 51 is about where it died. The open loop on fuel 1 is a bit curious. After frame 51 is where it was crank no start symptom.

FRAME: 49 TM: 138.2

ABSLT TPS($10) 32.2
ABSLT TPS($18) 33.3
CALC LOAD(%) 5.1
COOLANT(°F) 198
ENG SPEED($10) 1545
ENG SPEED($18) 1571
FUEL SYS 1 CLSD
FUEL SYS 2 CLSD
IAT(°F) 109
IGN ADV(°) 30.0
LT FTRM1(%) 1.6
LT FTRM2(%) 2.3
MAP("HG) 5.9
MIL STATUS($10) Off
MIL STATUS($18) Off
O2S11(V) 0.000
O2S12(V) 1.000
O2S21(V) 0.040
O2S22(V) 1.000
OBD2 STAT CA
ST FTRM11(%) 18.8
ST FTRM21(%) 16.4
ST FTRM1(%) 19.5
ST FTRM2(%) 17.2
VEH SPEED(MPH) 39

------------------------------

FRAME: 50 TM: 141.0

ABSLT TPS(%) 12.6
ABSLT TPS(%) 13.3
CALC LOAD(%) 3.9
COOLANT(°F) 196
ENG SPEED(RPM) 1298
ENG SPEED(RPM) 1539
FUEL SYS 1 CLSD
FUEL SYS 2 CLSD
IAT(°F) 109
IGN ADV(°) 22.5
LT FTRM1(%) -0.8
LT FTRM2(%) 0.0
MAP("HG) 5.9
MIL STATUS Off
MIL STATUS Off
O2S11(V) 0.000
O2S12(V) 1.000
O2S21(V) 0.040
O2S22(V) 1.000
OBD2 STAT CA
ST FTRM11(%) 0.0
ST FTRM21(%) 0.0
ST FTRM1(%) 0.0
ST FTRM2(%) 0.0
VEH SPEED(MPH) 38

------------------------------

FRAME: 51 TM: 143.9

ABSLT TPS($10) 12.6
ABSLT TPS($18) 12.9
CALC LOAD(%) 2.4
COOLANT(°F) 196
ENG SPEED($10) 792
ENG SPEED($18) 779
FUEL SYS 1 OPEN1
FUEL SYS 2 CLSD
IAT(°F) 109
IGN ADV(°) 8.0
LT FTRM1(%) -4.7
LT FTRM2(%) -1.6
MAP("HG) 5.9
MIL STATUS($10) Off
MIL STATUS($18) Off
O2S11(V) 0.000
O2S12(V) 1.000
O2S21(V) 0.040
O2S22(V) 1.000
OBD2 STAT CA
ST FTRM11(%) 3.9
ST FTRM21(%) 3.9
ST FTRM1(%) 3.9
ST FTRM2(%) 3.9
VEH SPEED(MPH) 34

------------------------------

FRAME: 52 TM: 146.8

ABSLT TPS(%) 12.6
ABSLT TPS(%) 12.9
CALC LOAD(%) 1.2
COOLANT(°F) 194
ENG SPEED(RPM) 384
ENG SPEED(RPM) 376
FUEL SYS 1 CLSD
FUEL SYS 2 CLSD
IAT(°F) 113
IGN ADV(°) 8.0
LT FTRM1(%) -3.9
LT FTRM2(%) -0.8
MAP("HG) 5.9
MIL STATUS Off
MIL STATUS Off
O2S11(V) 0.000
O2S12(V) 1.000
O2S21(V) 0.060
O2S22(V) 1.000
OBD2 STAT CA
ST FTRM11(%) 5.5
ST FTRM21(%) 5.5
ST FTRM1(%) 5.5
ST FTRM2(%) 5.5
VEH SPEED(MPH) 20

------------------------------

FRAME: 53 TM: 149.6

ABSLT TPS($10) 12.6
ABSLT TPS($18) 12.9
CALC LOAD(%) 0.0
COOLANT(°F) 194
ENG SPEED($10) 0
ENG SPEED($18) 0
FUEL SYS 1 CLSD
FUEL SYS 2 CLSD
IAT(°F) 115
IGN ADV(°) 0.0
LT FTRM1(%) -3.9
LT FTRM2(%) -0.8
MAP("HG) 5.9
MIL STATUS($10) Off
MIL STATUS($18) Off
O2S11(V) 0.000
O2S12(V) 1.000
O2S21(V) 0.060
O2S22(V) 1.000
OBD2 STAT CA
ST FTRM11(%) 5.5
ST FTRM21(%) 5.5
ST FTRM1(%) 5.5
ST FTRM2(%) 5.5
VEH SPEED(MPH) 9

------------------------------

More ideas? Again, no lights/codes when it dies. After sitting a few minutes it starts up and sometimes will go a short distance and die again, or in this case I was able to drive home.
Possible something is getting heat soaked but can't pinpoint it. I've driven it hours with no issues.

Still clueless...

 

[J33Pfan]

Did you use Mopar replacement parts?

 

[LibertyCentral]

Did you use Mopar replacement parts?

Yes. Even if I didnt I would still expect a code. But, no codes on the new parts either. It was just a shot in the dark

 

[turblediesel]

Speaking of shots in the dark...

Most vehicles have a switch that kills the fuel pump in an accident, sometimes under a front interior kick panel.

A friend hit a big sharp edged pothole hard and set his off on a Saturn. Towed home, baffled, hit the reset button and back to normal.

My Mom had a Ford Escort with the intermittant quit symptoms you have and I suspected the switch was bad. It wasn't bad gas.

 

[LibertyCentral]

Speaking of shots in the dark...

Most vehicles have a switch that kills the fuel pump in an accident, sometimes under a front interior kick panel.

A friend hit a big sharp edged pothole hard and set his off on a Saturn. Towed home, baffled, hit the reset button and back to normal.

My Mom had a Ford Escort with the intermittant quit symptoms you have and I suspected the switch was bad. It wasn't bad gas.

 

[LibertyCentral]

Sorry, got a bit click happy there....
Good thought on the fuel pump. However, the fuel pressure is good when the event happens. Had a gauge attached to see if it was a fuel pump. Had ~50psi at all times. I originally thought it was a fuel pump, but the gauge proved otherwise.

 

[turblediesel]

Must be the confuser. It's overworking.

 

[LibertyCentral]

Replaced the confuser, I think it made it worse.

Also, had a wild thought and replaced the ignition switch thinking maybe the run circuit was hosed up. Well, no, back to the same old.

Still looking for ideas. I may try removing the remote start boxes next. But I had pulled the fuses to them prior so I don't expect any difference.

 

[LibertyCentral]

Still fighting this, was on the back burner for a bit due to other projects. So, I did pull the remote start boxes, that stopped the battery from dying after sitting a few days. Yes, that is a new problem.

Back to the dying random issue, I replaced the fuel pump just because, 180k miles probably due soon. Still no joy.

Would love any ideas if someone has any.

 

[daves06lrenegade]

You might want to put a couple 12v bulbs (or meters) on the fused lines feeding the PCM unit to see if the supplies may be dying at the time... Because it is not storing codes at the time of failure the PCM may be loosing power during the event and because it is "dead" at that time no codes stored... Also you might want to monitor the 5v power lines feeding the cam and crank sensors...
There are very cheap meters on ebay that would allow you to monitor power lines and if the go to 0v you got your answer(s)...
https://www.ebay.com/itm/New-Mini-D...hash=item33fda95f80:m:m3heZbY29E3ElAJapTS8QOw
Dave

 

[Billwill]

Fitting small meters to measure the voltages may work..have them inside the cabin so you can monitor them while driving.

The problem is that it may be a very small spike that you will not see in time. If you do this on the PCM for example...connect the meter to the supply voltage with one lead and the other lead must go to the PCM's ground point in case that is where the loose connection is.

There are many grounding points all over the Jeep..make use of the Locations Section in the Jeep KJ Service Manual to locate all of them and check them out.

My CRD used to suddenly cut out with no CEL posted. Start it up again and it would run a while and cut out again.
Turned out to be a clogged fuel filter but your fuel pressure seems good.

Probably a wiring problem somewhere which could be very hard to find!

 

[Billwill]

Speaking of shots in the dark...

Most vehicles have a switch that kills the fuel pump in an accident, sometimes under a front interior kick panel.

A friend hit a big sharp edged pothole hard and set his off on a Saturn. Towed home, baffled, hit the reset button and back to normal.

My Mom had a Ford Escort with the intermittant quit symptoms you have and I suspected the switch was bad. It wasn't bad gas.

Does the KJ not have a "roll over" sensor somewhere in the fuel tank to cut off fuel in a roll over?. I seem to recall seeing a post about this on one of the Jeep Forums years ago.

The OP's scan tool should pick up this up though.

 

[daves06lrenegade]

I got a 1997 Ford Ranger cheap at auction as a "won't run" ... Found an inertia switch on the passenger side firewall that had tripped.. One push and it came to life !
If nothing else the gas pickup tube would no longer be in the gas with a roll over
I would also be interested in finding if there is such a sensor...
Dave

 

[JasonJ]

Replaced the confuser, I think it made it worse.

Also, had a wild thought and replaced the ignition switch thinking maybe the run circuit was hosed up. Well, no, back to the same old.

Still looking for ideas. I may try removing the remote start boxes next. But I had pulled the fuses to them prior so I don't expect any difference.

With issues like this, removing the aftermarket remote start would have been the FIRST thing I did. Those things always cause issues.. eventually.

I'd absolutely second the suggestion by Dave up there regarding the 5v and 12v power line monitors.. the lack of DTC's is disturbing. His explanation/theory on why that is makes the most sense to me.